Process of and apparatus for cracking or converting oils



Oct. 21, 1924.

Q. P. AMEND PROCESS OF AND. APPARATUS FOR CRACKING CONVERTING OILS Filed Jun:

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0. P. AMEND PROCESS OF .AND APPARATUS FOR GRACKXNG OR CONVERTING OILS Filed June 8, 1917 Q 2 Sheets-Sheet 2 3 nuewtoz 077 Z an m M: Amen? Patented Oct. 21., 1924.

UNITED ta;

OTTO P. AMEND, OF NEW YORK, N. Y.

PROCESS OF AND AJPPTUS JFOB, CRACKING 0R CONVEBTING'OES.

Application filed June}, 1917. Serial No. 178,686.

To all whom it may concern:

Be it known that I, Orro P. AMEND, a citizen of the United States, residing .in the city of New York, county of New York, and State of New York, have invented a certain new and useful Process of and Apparatus for Crackingor Converting Oils, of which the following is a specification.

This invention relates broadly to the art of cracking crude petroleum, heavy naphthas, kerosene, and higher-boiling hydrocarbon distillates or residuals, and converting the same into lower-boiling hydrocarbons, suitable for use in internal combustion engines, and for all other purposes for which the low-boiling petroleum distillates are used. The process is ap licable either to hydrocarbons of the para n'or of the naphthene or polymethylene series, or 'to mixtures of hydrocarbons of any series. The process is preferably applicable to any of the hi herboilin petroleum distillates, such as ero: sene, filexican distillates, gas oils, and fuel oils.

By my process I am 'able to secure any desired suitable vaporizing or cracking temperature within the hydrocarbons, at the same time that the sides and bottom of the still or digester are relativelycool, and the ability of the metal of the containing vessel to resist pressure is consequently not seri-, ously impaired, and much higher pressures may safely be utilized than can be safely used by any process of external heating of oil in large stills. A pressure in excess of one hundred pounds may be safely used with large stills, of say from 600 to 1000 barrels capacity, with'my process, whereas such pressures are not practicable on a large scale in any process in which the oil is heated by external heating. I secure this result by internal heating of the oil itself, by means of one or more high resistance electrical heating elements, preferably of carbon, and preferably wholly or partly immersed in the oil in the still or digester, and heated to the desired cracking temperature; One of the chief difficulties hitherto ex perienced in attemptsat cracking and converting high boiling hydrocarbon into a .low boiling distillate, by the use of resistors submerged within the oil and heated to incandesoence, consists in the fact that when the resistor was of any size and was heated to the high heat required for successful crackin of the kerosene or other high boiling by rocarbons, in the case of kerosene, a heat of from a cherry red to a white heat bein generally required, the heated resistor repe ed the oil and prevented intimate contact,-and the oil at a distance from the resistor was merely vaporized without being cracked or converted into lighter hydrocarbons. The greater part of the condensate obtained was, therefore, unconverted oil. I have found that to overcome this repel- Ient force of the heated resistors, and to enforce contact or close proximity of the oil or oil vapors with the incandescent resistors, pressure is required. The function of pressure in myprocess, while-it incidentally raises the boiling point and the temperature of the liquid, and although it is primarily to enforce close contact between the oil or oil vapors and the highly heated incandescent resistors, it also largely arrests the gasification of the oil. The amount of pressure required in any particular case to produce the best results, depends on the character of the oil treated, and on the temperature of theresistors, and on the size of the receptacle. While a pressure of only from about two atmospheres upward may be used with kerosene in a very small retort, better results, both in the case of kerosene and other oils, are obtained from pressures considerably in excess of four to fifteen atmospheres. Generally small stills or retorts are preferred to large ones. {It is obvious that the more pressure i applied; to the oil to keep it in actual contact with the incandescent resistors, the more cracking and the less vaporization Without conversion will take place, and that with an easily gasifiable oil v pressures in excess of four atmospheres should preferably be used. With a s oil or. fuel oil, I prefer to use pressures of tween six and ten atmospheres. Genery it is desirable that the higher the tenureture of the resistors, the greater shoud the pressure used, although with highly incandescent resistors pressures above tea atmospheres are unnecessary. W here the carbon or other high resistance conductor is heated to a bright red, or between a bright red and a white heat, pressures ranging fro about 50 to pounds to the square inch are preferable. Higher pressures are preferable to. very low pressures, for the reason that the higher the pressure used, the moreintimate is the contact of the hydrocarbon liquid or vapor with' the heated carbon or other resistance conductor, or source of heat, and the less gasification takes place and the more volatile and uniform is the resulting product. ll have, however, successfully converted kerosene in a small retort into a lowten atmospheres and over.

This electric heating element may be either entirely submerged or only partially immersed in the oil, or it may be entirely above the-surface of the liquid, or one or more of such electric heating elements may be either wholly submerged or partially immersed in the oil, and at the same time, one or more of such electric heating elements may be inserted in a suitable space above the liquid to secure an intimate contact with the evolved hydrocarbon vapors. Where the electric heating element is wholly or partly above the surface of the liquid, all air should first be removed, preferably by injecting an inert gas free from oxygen, such as hydrogen gas or natural gas. There is a distinct advantage in having one or more electric heating elements located above the surface of the oil in the still or container, or partially submerged and partially above the surface of the liquid, as by this means more intimate contact is had between the heating element and the evolved hydrocarbon vapors, and such liquid hydrocarbons as have only been vaporized without cracking orconversion into lighter vapors, because of the conduction of heat from the heating element in the liquid, are again subjected in the vapor stage to contact with a second electric heating element, preferably electrically heated graphitic carbon, and are cracked and converted into low boiling hydrocarbon vapors before emerging from the still or container. By this means, the percentage of low boiling hydrocarbons in the resulting condensate is greatly increased.

' It is desirable that one or more of these electric heating elements, preferably one or more electrically heated carbon tubes, of small diameter, should substantially fill a cross section of the vapor dome or the pipe or outlet leading to the condenser. In this way, all of the evolved hydrocarbon vapors must pass in close proximity to the incandescent carbon.

I have found that high resistance conductors made of carbon are most satisfactory, both because of the saturated character of the low boiling condensate obtained by their use, and because any carbon resulting from the cracking of the hydrocarbons,.on being deposited on the resistors does not affect them injuriously, whereas the formation of a hard carbon crust on metallic resistors, impermeable to the hydrocarbon vapors, which usually takes place, seriously affects their successful operation. ll prefer to use resistors of graphitic carbon as they are of higher resistance than ordinary carbon. The high resistance conductor may be in the form of a rod, plate, sheet or tube or any other form. Of the above forms ll prefer to use suitable hollow carbon tubes, preferably made of graphitic carbon.

By the use of internal heat electrically ap plied, I am able to regulate to a nicety the actual heating within the body of the oil. This more perfect regulation of the heat within the hydrocarbons enables a more constant quality of cracked product to be produced than is possible with external heating of the still.

The accompanying drawings illustrate types of apparatus, forming part of my invention, which may be employed in practicing the process herein described, although ll desire to have it understood that other forms of apparatus may also be used.

Referring to the drawings, Figure 1 shows, more or less diagrammatically, partly in section and partly in elevation, a substantially complete apparatus for practicing the process.

Figure 2 shows substantially the same type of apparatus except that the pipe connecting the outlet of the still to the condenser is not inclined as it is in Figure 1, and, further, the pressure valve is in a different location, and

Figure 3 shows a still provided with a modified form of apparatus for heating the contents thereof.

Referring particularly to- Figure 1, A is a still having an oil inlet a and an inlet for inert gas 1) extending nearly to the bottom of the still. The still is heated by means of a submerged carbon resistor 0, preferably in tubular form as shown, the said resistor being provided with suitable terminals (l and a properly insulated from the walls of the still. The upper portion of the still may also be provided with a carbon resist-or f for subjecting the oil vapors to heat, said resistor being preferably in tubular form, and being provided with suitable terminals 5 and It also properly insulated from the walls of the still. The outlet or gooseneck B of the still is inclined as shown, whereby a more or less reflux effect is obtained. The upper end of said gooseneck is provided with a suitable pressure valve C, whereby the con-tents of the still and vapors therefrom. may bekept at any predetermined pressure. The gooseneck of the still con- MID nects with a cooling coil or condenser D,

sitioned within a cooling 'acket or casing said jacket bein provide with a suitable inlet 2' and outlet j %or the cooling agent,'such as water. The outlet 7: from the condenser leads to a suitable trap for condensed liquid collector F having a bafiie Z and a suitable draw-off pipe m. Thetrap is provided with an outlet n for non-condensed vapors or gases, said outlet leading to a suitable compressor G, diagrammatically shown, wherein said vapors or gases are compressed, whence they pass through the outlet 0 of the compressor into an expansion chamber H. The effect of expanding the mixture of compressed gases and vapors in chamber H results in a reduction of the temperature thereof to such extent that practically all the condensable vapors are liquefied in said chamber and may be drawn off through pipe p. The expansion chamber H is provided with a gas or vapor outlet 9 through which the residuary, uncondensed vapors or gases pass, whereupon they may be subjected to such further use or treatment as is found desirable.

Referring now to Figure 2, A is a still having an oil inlet a and an inlet for inert gas 6 extending to nearl the bottom of the still. The still is heated y means of a sub-' merged carbon resistor 0', preferably in tubular form as shown, the said resistor be- .ing provided with suitable terminals d and e properly insulated from the walls of the still. The upper portion of the still may also be provided with a carbon resistor f for subjecting the oil vapors to heat, said resistor being preferably in tubular form, and being provided with suitable terminals g and. k also properl insulated from the walls of the still. B of the still is substantially horizontal as shown and is provided, at its end adjacent to the outlet of the still, with a pressure valve C. The ooseneck of the still connects with a cooling coil or condenser D, gsitioned within a cooling jacket or casing said jacket being provided with a suit able inlet 11' and outlet j for the cooling agent, such as water. The outlet k from the condenser is provided with a pressure valve C and leads to a suitable trap for condensed liquid, namely, collector F having a baflle Z and a suitable draw-off pipe m. The trap is provided with an outlet n for noncondensed gases or vapors, said outlet leading to a suitable compressor G, diagrammatically shown, wherein said vapors or gases are compressed, whence they pass through the outlet 0 of the compressor into an expansion chamber H. The effect of expanding the mixture of compressed gases and vapors in chamber H results in the reduction of the temperature thereof to such extent that practically all the condens- T e outlet or gooseneck able vapors are liquefied in said chamber and may be drawn off through pipe 9. The

expansion chamber H is provided with a gas or vapor outlet 9 through which the stantially the same form described in con-.

nection with Figures 1 and 2, the main difference in the method of heating consisting, however, is spacing the electrodes apart, whereby arcing is produced within the body of the oil. The electrodes 0 0 are suitably insulated from the still and are provided with suitable electrical connections 6 12 respectively. It will be understood that the StillillllStIfliGd in Figure 3 may also be provided with means, similar to that shown in Figures 1 and 2 for electrically heating the oil vapors. To accomplish this result, the outlet from the still may contain a suitable resistor f preferably in tubular form, having suitable termmals g and k From the foregoing description of the apparatus, its mode of use will be readily understood by those skilled in the art from the hereinafter detailed description of applicants process. It will be observed that the pressure valves C, C in Figures 1 and 2, respectively, are positioned'intermed'ia-te the still and the condenser. The pressure obtained is created by and is directly dependent upon the temperature of the resistors and therefore upon the amount of electric current which is employed in the operation, and is produced by the vaporization, dissociation and expansion of the hydrocarbons.

In my process, the desired heat to produce dissociation of the liquid hydrocarbons is applied directly within the liquid hydrocarbons, or their resulting vapors, by contact With or proximity to the heated rcsistors, the resistors being heated to any desired heat by the passage of a suitableelectric current. The resistors may be entirely submerged Within the oil, or may be partly above the liquid, so that the evolved hydrocarbonvapors, as well as the liquid hydrocarbons, may come in contact with heated resistors. By this means, a high local dissociating heat can be applied to the interior of the hydrocarbon liquid or vapor, within the still or digester, without'the necessity of first heating the metal of the still or digester itself, in order for the latter to transmit the heat to the hydrocarbons. The extent to which the metal sides and bottom of the still or digester will be heated, will deiso pend upon the amount of heat transmitted by the heated oil to the metal, instead of the heat required for vaporization being transmitted through the metal to the oil. By my process, the greatest heat is applied where it is most desired, that is, within the mass of oil or oil vapors.

Because of the capability in my process to combine high local dissociating heats within the oil, or its vapors, with moderate pressures I am able successfully to crack kerosene, that is, a hydrocarbon having a range of boiling points above 130 C. and below 260 C.

The cracking and dissociation of the hydrocarbons induced by the contact with the incandescent carbon resistors produces a very rapid evolution of low boiling hydrocarbon vapors and rapid resulting increase of pressure. In order to obtain by my process a satisfactory conversion of kerosene into low boiling hydrocarbons, a small still should be used equipped with carbon conductorsof relatively large surface in proportion to the volume of oil, and the carbon resistors should preferably be heated to a bright red, or from a bright red to a white heat, although heats as low as a cherry red may be used with inferior results. here carbon resistors are used heated to the above heats, there is comparatively little formation of tar and evolution of gas, the deposited carbon being porous and flaky and easily removable, and the higher the temperature of the carbon resistors, the lighter in gravity is the condensate, and the freer it is from olefines and other unsaturated hydrocarbons, and from coloring matter.

In general, with all the hydrocarbons, the lower the boiling points, the higher is the dissociating temperature which should be used. Dissociation temperatures for gas oils and fuel oils of as low as about 500 C., and

as high as a white heat of carbon, may be used, but with these high boiling oils I prefer to use temperatures from a cherry red to a temperature corresponding to that of a bright red heat of carbon, or approximately from 750 C. upwards. Pressures in excess of four and under ten atmosphere as sufficient, although higher pressure may be used.

With graphitic carbon resistors, a current of relatively low voltage and high amperage should be used. The voltage preferably ranges between 10 and 25 volts.

The time required to begin dissociation of the hydrocarbons, is extremely short by my -electrical process. vaporization and dissociation begin almost instantaneously and the desired dissociation increases with increase in the pressure.

As-the temperature of the metal digester was under 200 C. when the pressure was at 175 pounds, it is practicable to build Letaaes digesters or stills which can stand a pres sure, at such a heat, up to 500 pounds or more. It is not safe to operate large stills heated by external firing over a pressure of 200 pounds.

The amount of current required to produce agiven heat in any case, will, of course. depend largely on the number, diameter, or thickness and length and specific resistance of the resistors used.

In heating the high resistance conductors, the following general rules should be observed. The resistance of a conductor varies directly with its length and inversely with its area in cross section. The rise of temperature in a given conductor is proportional directly to the square of the current strength, and to the specific resistance, and is inversely proportional to the cube of the radius, and to the emissive (radiative) power.- The heat lost by the conductor by radiation is greater, the greater the difierence between its temperature and that of the surrounding medium. A peculiarity of carbon is that when heated to bright incandescence, its resistance decreases about one-half. This tendency may be largely 0&- set by increasing the length of the carbon conductor and so increasing the resistance. Graphitic carbon maintains a higher resistance, when heated, than ordinary carbon.

Where additional hydrogen gas or natural gas is used in the cracking operation,- because ofthe fact that the hydrogen gas carries off with it-a considerable amount of finely divided hydrocarbon vapors which need compression in order to he recovered,-the cracked vapors are preferably first cooled, in order to condense the heavy hydrocarbons and the more easily condensed lighter condensate, and the remaining uncondensed vapors-and gases, may then be mechanically compressed, preferably in the cylinders of a suitable gas compressor, to pressures generally in excess of one hundred pounds, and preferably to over two hundred and fifty pounds to the square inch, and then condensed, preferably by rapid expansion, which expansion may be availed of in any suitable type of engine for accomplishing work.

The condensation in the condenser may be had at atmospheric pressure or under substantially the same pressure as in the still or digester. In the latter case the desired pressure is obtained by regulating a valve a t the outlet end of the condenser coil, as shown, for example by C in Figure 2 of the cally continuous current of vapors may be released to the condenser. I

From the upper part of the still, and preferably from the upper part of the vapor dome or' tower in the upper part of the still, aninclined conduit or runback preferably leads up to the condenser coil. This inclined conduit, while not necessary, is distinctly advantageous as it obviates the necessity of making the vapordome or tower too high and produces the effect of increas-' ing the length of the reflux condensation zone. 'The operation of the air cooled inclined conduit is to condense the heavier fractions of the distillate and antmatically' to return them to the heated zones of the still for further treament. This inclined conduit may be of any desired length, preferably from twenty to forty feet long, its diameter depending upon the size of the still and the amount of vapors requiring to pass over in a given time. A suitable valve is placed at the upper end of the runback.

By this means the heavier fractions of the distillate are subjected to condensation under pressure inthe runback, and subjected again to the dissociating contact with the heated carbon, the lighter vapors passing through the valve "upon the regulated pressure being reached and over to the condenser.

I have found that the effect of incandescent carbon resistors, in cracking kerosene and other higher boiling hydrocarbons under pressure, is most remarkable. In previous cracking processes for the treatment of kerosene and other high boiling hydrocarbons, very heavy gas losses are had, ranging from a minimum oftwenty per cent for fuel oil to a maximum of sixty per cent for kerosene, and also heavy deposition of carbon. That is, the two end products of the hydrocarbon, viz, hydrogen and carbon, are formed in very considerable quantities.

The elfect of the electrically produced heat applied to the hydrocarbons through the incandescent resistors, is to crack the kerosene and other heavy hydrocarbons and convert them into low boiling hydrocarbons with a minimum of'gas losses and of carbon deposition, when even such high temperatures are used as would normally, by any process of external heating, completely decompose the hydrocarbon into fixed gases and carbon. In other words, the effect of the cracking of the hydrocarbon under pressure, by the use of highly incandescent carbon is highly protective to the liquid hydrocarbons. A further feature of my process is that the condensates obtained are composed almost wholly of saturated hydrocarbons, or of a minimum of unsaturated oxidizable hydrocarbons, even where the very high cracking temperatures are used.

The condensate obtained is a crude condensate which .1 generally requires further 'moving all unsaturated hydrocarbons by the use of cold concentrated sulphuric acid may be used. I

By high-boiling hydrocarbons, I mean to include all liquid hydrocarbons having boiling points about 150 C.

By kerosene, I mean to include all fractions distilled liquid hydrocarbons, either crude or refined, having boiling points above 150 C. and below 250 0., or having a distillation range not substantially in excess of those limits.

In view of the foregoing disclosure, it

will be obvious to those skilled in the art that my process may be carried out with different steps and with the assistance of different apparatus from that described, Without, however, departing from the scope of my invention, and accordingly, I intend that all matter contained in the above description, shall be interpreted as illustrative and not in a limiting sense.

Having described the invention, what I claim is: I

1. The process of converting oils having boiling oints about 150 G. into a low-boiling by rocarbon distillate, which consists in maintaining in engagement with 'a rela tively stationary bodyof the liquid hydrocarbon to be converted a non-metallic resistance conductor, causing a low voltage,

high amperage electric current i to pass vapors in excess of two atmospheres and below .thirty atmospheres, and collecting and condensing the resultin cracked vapors.

2. In an apparatus or cracking or converting heavy hydrocarbons, a still adapted to contain a relatively large and relatively stationary liquid body of oil, a carbon resistor positioned withinthe still and adapted to contact with the liquid body of oil therein, meansfor passing an electric current through the resistor, means for introducing a fixed gas into the still, means for. maintaining the still under controlled superatmospheric pressure, and means for withdmimlwing and condensing vapors from the sti 3. The process of raising the Baum gravity of oils, which consists in subjecting a relatively stationary liquid body of the oil, in a confined space, while introducing a fixed gas, to intimate contact with a carbon resistor in engagement with the oil and its g; i neiaaaa heated to incandescence by the passage of an electric current, while subjecting both the liquid hydrocarbon and the evolved vapors to a controlled pressure in excess of two and below thirty atmospheres, and collecting and condensing the resulting vapors. I

4%. The process of converting oils, which consists in electrically maintaining a large carbon tube resistor adapted to permit circulation therethrough at a decomposing incandescent temperature in local contact with a relatively stationary mass of oil, in a still, while maintaining a controlled pressure in excess of five atmospheres, upon the liquid hydrocarbon and its evolved vapors, and collecting and condensing the resulting vapors.

5. In an apparatus for crackin or converting heavy hydrocarbons, a stil adapted to contain a relatively large and quiescent liquid body of oil, a tubular carbon resistor positioned within the still and adapted to contact with the liquid oil over the rela tively large area presented by the continuous inner and outer surfaces thereof, means for passing an electric current throu h the resistor, means for maintaining the stlll under controlled. superatmospheric pressure, and means for withdrawing and condensing oil vapors from the still.

8. In an apparatus for increasin the amount of light hydrocarbon fluids o tainable from a given quantity of native hydrocarbon oil or residuum the combination, with a closed retort for holding the'materials, of electrical heating means located in.

said retort interior com rising a plurality of resistors, one of whic is located in the retort space for fluids, and another in the retort space for vapors, and an electric circuit including said resistors.

7. In an apparatus for cracking fluid hydrocarbons the combination, wit a' closed retort having a zone for fluids and a zone or vapors, of a carbon resistor located in the fluid zone, another carbon resistor located in the vapor zone, and means for passing electric currents through mth resistors.

8. The process of converting heavy hydrocarbon oils into low boiling hydrocarbon distillates consisting in subjecting a relatively stationary body of such heavy hydrocarbon oils, to direct contact with an electrically heated non-metallic resistor immersed in the body of oil, while the My of oil iskept under pressure.

9. The process of converting heavy hydrocarbon oils into low boiling hydrocarbon distillates consisting in subjecting a relatively stationary body of such heavy hydrocarbon oils, to direct contact with an electrically heated nonmetallic resistor immersed in the body of oil, while the body of oil is kept under pressure, and refluxing the unconverted vapors.

10. The process of converting heavy hydrocarbon oils into low boiling hydrocarbon distillates consisting in subjecting a relatively stationary body of such heavy hydrocarbon oil, to direct contact with a. carbon resistor immersed in the body of oil electrically heated to a temperature between a' red and a white heat while the body of oil is kept under pressure.

11. The process ofconverting heavy hydrocarbon oils into low boiling hydrocarbon distillates consisting in subjecting a relatively stationary body of such heavy hydrocarbon oil, to direct cont-act with a carbon resistor immersed in the body of oil electrically heated to a temperature between a red and a white heat while the body of oil is kept under pressure and refluxing the unconverted vapors.

12. The process of convertin kerosene into a low boiling hydrocarbon istillate consisting in subjecting a relatively stationary body of liquid kerosene, to direct contact with a non-metallic resistor iersed in the relatively stationary body of kerosene electrically heated to a temperature between a red and a white heat while the body of herosene is kept under pressure.

In testimony whereof l have signed my name to this specification.

- @TTU 1P. AMEND. 

